c - Passing an array of pointers by reference -

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i'm trying commands keyboard in similiar fashion command line args int main( int argc, char *argv[] )but in separate function. when parse , print them within scope of getcmd() function looks , behaves intended, return main function become bunch of garbage. questions below code.

#include <stdio.h> #include <time.h> #include <stdlib.h> #include <string.h>  void getcmd(char *cmd, char *args[]) {     char input[81] = { 0 };     char *next_token = null;     printf("$ ");     fgets(input, 81, stdin);     input[strcspn(input, "\n")] = 0;     cmd = strtok_s(input, " ", &next_token);     if (!strcmp(cmd, "mv"))     {         args[0] = strtok_s(null, " ", &next_token);         args[1] = strtok_s(null, " ", &next_token);         printf("\n\n%s\n%s\n%s\n\n", cmd, args[0], args[1]);     } }  int main(void) {     char *cmd = null, *args[5];      cmd = (char *)calloc(20,sizeof(char));     (size_t = 0; < (size_t)5; i++)     {         args[i] = (char *)calloc(20,sizeof(char));     }     getcmd(cmd, args);     printf("\n\n%s \n%s\n%s", cmd, args[0], args[1]);     return 0; }

i don't think relevant i'm using vs 2015 community visual c++ compiler on 64 bit processor, windows 7 os.

my questions:

  • how should pass cmd , args[] reference?
  • are there accepted idioms deal sort of situations?

i've looked trough few of similiar questions , couldn't find solution works in context, if question duplicate, tell me , i'll close it.since i'm new stackoverflow question formatting tips appreciated. cheers! (:

strtok_s() return pointer buffer it's parsing (input here).

input lives on getcmd() stack. dies moment getcmd() returns. on addresses pointing input , had been stored in args's elements not point valid memory more.

the code needs allocate fresh memory , copy strtok_s() returned pointer to.

have on ow can done:

#include <stdio.h> #include <stdlib.h> #include <string.h>  void getcmd(char **pcmd, char *args[], size_t s) {     char input[81] = { 0 };     char *next_token = null;     printf("$ ");     fgets(input, 81, stdin);     input[strcspn(input, "\n")] = 0;     (*pcmd) = _strdup(strtok_s(input, " ", &next_token));     if (!strcmp(*pcmd, "mv"))     {         args[0] = _strdup(strtok_s(null, " ", &next_token));         args[1] = _strdup(strtok_s(null, " ", &next_token));         printf("\n\n%s\n%s\n%s\n\n", *pcmd, args[0], args[1]);     } }   #define args_max (5)  int main(void) {     char *cmd, *args[args_max] = {0};      getcmd(&cmd, args, args_max);     printf("\n\n%s \n%s\n%s", cmd, args[0], args[1]);      /* clean up. */     free(cmd);     (size_t = 0; < args_max; ++i)     {       free(args[i]);     }      return 0; }

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